A possible archaic precursor of the octocoral structural plan from the Ordovician of Estonia

A new species and genus of colonial coral, Lindaphylon solovjevi, from the Upper Ordovician of Estonia is described in detail. The colony has a zonation similar to the zonation structure of the mesogleal skeleton of octocorals, since it consists of a narrow axis and a surrounding wide cortex of small calcite sclerites and a system of large solenia. Corallites present 12 sclerosepta in a wide shallow cup. A new family Lindaphylonidae and an order Lyndaphylonaceae are based on these features, and a new order placed in the subphylum Anthozoa as incertae sedis. A comparative study of skeleton formation and mesenteric apparatus symmetry in different groups of coral polyps is considered in detail.